Universität zu Köln

Schuette, Christoph and Garst, Markus ORCID: 0000-0001-5390-3316 (2014). Magnon-skyrmion scattering in chiral magnets. Phys. Rev. B, 90 (9). COLLEGE PK: AMER PHYSICAL SOC. ISSN 1550-235X

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Abstract

Chiral magnets support topological skyrmion textures due to the Dzyaloshinskii-Moriya spin-orbit interaction. In the presence of a sufficiently large applied magnetic field, such skyrmions are large-amplitude excitations of the field-polarized magnetic state. We investigate analytically the interaction between such a skyrmion excitation and its small-amplitude fluctuations, i. e., the magnons in a clean two-dimensional chiral magnet. The magnon spectrum is found to include two magnon-skyrmion bound states corresponding to a breathing mode and, for intermediate fields, a quadrupolar mode, which will give rise to subgap magnetic and electric resonances. Due to the skyrmion topology, the magnons scatter from an Aharonov-Bohm flux density that leads to skew and rainbow scattering, characterized by an asymmetric differential cross section with, in general, multiple peaks. As a consequence of the skew scattering, a finite density of skyrmions will generate a topological magnon Hall effect. Using the conservation law for the energy-momentum tensor, we demonstrate that the magnons also transfer momentum to the skyrmion. As a consequence, a magnon current leads to magnon pressure reflected in a momentum-transfer force in the Thiele equation of motion for the skyrmion. This force is reactive and governed by the scattering cross sections of the skyrmion; it causes not only a finite skyrmion velocity but also a large skyrmion Hall effect. Our results provide, in particular, the basis for a theory of skyrmion caloritronics for a dilute skyrmion gas in clean insulating chiral magnets.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Schuette, Christoph UNSPECIFIED UNSPECIFIED UNSPECIFIED Garst, Markus UNSPECIFIED orcid.org/0000-0001-5390-3316 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-428376
DOI:	10.1103/PhysRevB.90.094423
Journal or Publication Title:	Phys. Rev. B
Volume:	90
Number:	9
Date:	2014
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	1550-235X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SPIN TRANSFER; DYNAMICS; FERROMAGNETS; MOMENTUM; SOLITON; MOTION; MODES; MNSI; WAVE; CRYSTALS Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/42837